<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>后盾人</title>
    <style>
        main {
            border: solid 3px black;
            height: 220px;
            width: 610px;
            margin: 0 auto;
            padding: 20px;
        }

        span {
            border: solid 2px blue;
            width: 300px;
            float: left;
            height: 50px;
        }

        span:nth-of-type(2) {
            float: right;
        }
    </style>
</head>

<body>
    <main>
        <span>houdunren</span> <span>hdcms</span>
    </main>
</body>

</html>